[Up]    Abdominal musculature    [Thoracic mm.]

The muscle labelled A is the two portions of the transected external abdominal oblique muscle (EAO). Notice that the muscle fibers run in a caudoventral direction. The underlying internal abdominal oblique muscle (IAO), B, is made up of fibers which course in the cranioventral direction. B2 is the cut aponeurosis of the IAO, under which we find the transverse abdominus muscle, C. The fibers of this third muscle run dorsoventrally. The aponeuroses of the EAO and IAO muscles, on each side, fuse to form a sheath over two strap muscles, the rectus abdominus muscles, D. The fibers of the rectus abdominus muscles course craniocaudally. The fused aponeuroses of the EAO and IAO muscles  fuse with the aponeurosis of the transverse abdominus muscles on the ventral midline, between the two rectus abdominus muscles, to form the linea alba (literally, the white line). NOTE: On an exam, I will not accept the abreviations use here (EAO, IAO). You must write out the whole name. I used them here to save space.